SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '021ec8354775c4d923d83318c8bc19a4bb772f8cd03aec8aeabdab432fabe94d' 
  AND token = 'GbZ1rwzyKhjmDOFqxQbT3sKVy6twP3rhchKNwGYcrjM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}